size constancy
Let's look at the available choices and see which matches the description given.
size constancy
* This pretty much matches what the student is saying. He looks at his hand and perceives it as being larger than he expects.
shape constancy
* The student wasn't yelling about having extra fingers, or an oddly shaped hand. So it's the shape he expected. But not the size he expected. So this is the wrong answer.
brightness constancy
* Once again, the student is saying something like "my hand is glowing!" or "my hand is dark!". So not the right answer.
color constancy
* The student isn't saying anything about his hand being an unusual color. So this too isn't the right answer.